Biology subjects

Olsson, N.

Publications and source records attributed to Olsson, N..

7 recordsLinked to original sources

bioRxiv2026

Site-specific combinatorial ubiquitination drives the targeted degradation of plasma membrane proteins

Cullin-RING E3 ligases (CRLs) ubiquitinate their substrates by recruiting them to complexes containing ubiquitin-conjugating enzymes (UCEs). Ubiquitination proceeds through the transfer of ubiquitin from UCEs to substrate lysines, but the specificity of lysine ubiquitination has not been widely investigated in cells. In this study, we use global ubiquitination profiling to identify sites in the kinase domains of receptor tyrosine kinases (RTKs), EGFR and Her2, that undergo CRL-mediated ubiquitination in cells treated with heterobifunctional degrader molecules. We find that VHL- and Cereblon-dependent degraders trigger the ubiquitination of a common subset of accessible lysines. Using mutagenesis, we show that the number of available ubiquitination sites specifies the extent of RTK degradation. Furthermore, introduction of non-native sites mostly fails to rescue clearance of lysine-deficient RTK mutants. These results highlight the specificity with which UCEs ubiquitinate their substrates and suggest that the ubiquitination of multiple sites governs the efficacy of degraders targeting plasma membrane proteins.

cell biology↗

bioRxiv2026

A multiomic lifespan signature in genetically diverse, diet-restricted mice

Dietary restriction extends lifespan across model organisms, but the plasma molecular changes mediating this effect remain incompletely characterized. We present a longitudinal multiomic analysis of 2,234 plasma samples from 960 Diversity Outbred mice subjected to intermittent fasting or caloric restriction and followed to natural death. Using mass spectrometry, we quantified 1,512 metabolites, lipids, and proteins and mapped their associations with diet, age and longevity. DR-induced molecular changes scale with caloric intake and modulate inflammatory, lipid catabolism, and oxidative stress pathways. Aging showed a biphasic signature with sharp acceleration beyond 85% of lifespan, demarcating terminal decline. Mediation and survival modeling both identified superoxide dismutase (SODE) and vascular cell adhesion molecule (VCAM1) as top lifespan predictors. Genetic analysis revealed 9,599 QTL, nine of which coincided with previously identified lifespan QTLs, and were largely related to immune regulation. These findings provide a rich multiomic and genetic resource for the aging research community.

systems biology↗

bioRxiv2025

Platform-dependent effects of genetic variants on plasma APOL1 and their implications for kidney disease

Mutations in apolipoprotein L1 (APOL1) are strongly associated with protection against parasitic infections and increased risk of kidney disease in individuals of African ancestry. To better understand the mechanisms underlying APOL1-related pathologies, we examined genetic drivers of circulating APOL1 in individuals of African and European ancestry from four independent cohorts (UK Biobank, AASK, deCODE, and Health ABC) using three proteomic technologies (Olink, SomaLogic, and mass spectrometry). We found that disease-associated APOL1 G1 and G2 variants are strong cis-pQTLs for plasma APOL1 measured by Olink and SomaLogic, but not mass spectrometry. Critically, the direction of variant effects differed between proteomic platforms, being positive with Olink and negative with SomaLogic. We identified an additional APOL1 missense variant (rs2239785), common in Europeans, exhibiting the same platform-dependent directional discrepancy. Furthermore, variants in the kallikrein-kinin system (KKS), involving KLKB1, F12, and KNG1, and their genetic interactions showed strong trans-pQTL effects on APOL1 measured by Olink, but not SomaLogic. These platform-dependent discrepancies raise the possibility that both intrinsic APOL1 mutations and extrinsic KKS activity induce conformational changes in the APOL1 protein that are differentially recognized by the proteomic platforms.

genetics↗

bioRxiv2020

Inter-domain dynamics drive cholesterol transport by NPC1 and NPC1L1 proteins

Transport of LDL-derived cholesterol from lysosomes into the cytoplasm requires NPC1 protein; NPC1L1 mediates uptake of dietary cholesterol. We introduced single disulfide bonds into NPC1 and NPC1L1 to explore the importance of inter-domain dynamics in cholesterol transport. Using a sensitive method to monitor lysosomal cholesterol efflux, we find that NPC1s N-terminal domain need not release from the rest of the protein for efficient cholesterol export. Either introducing single disulfide bonds to constrain lumenal/extracellular domains or shortening a cytoplasmic loop abolishes transport activity by both NPC1 and NPC1L1. The widely prescribed cholesterol uptake inhibitor, Ezetimibe, blocks NPC1L1; we show that interface residues that lie at the interface between NPC1L1s three extracellular domains comprise the drugs binding site. These data support a model in which cholesterol passes through the cores of NPC1/NPC1L1 proteins; concerted movement of various domains is needed for transfer and Ezetimibe blocks transport by binding to multiple domains simultaneously.

biochemistry↗

bioRxiv2019

Exercise conditioned plasma dampens inflammation via clusterin and boosts memory

Physical exercise seems universally beneficial to human and animal health, slowing cognitive aging and neurodegeneration. Cognitive benefits are tied to increased plasticity and reduced inflammation within the hippocampus, yet little is known about the factors and mechanisms mediating these effects. We discovered \"runner\" plasma, collected from voluntarily running mice, infused into sedentary mice recapitulates the cellular and functional benefits of exercise on the brain. Importantly, runner plasma reduces baseline neuroinflammatory gene expression and prominently suppresses experimentally induced brain inflammation. Plasma proteomic analysis shows a striking increase in complement cascade inhibitors including clusterin, which is necessary for the anti-inflammatory effects of runner plasma. Cognitively impaired patients participating in structured exercise for 6 months showed higher plasma clusterin levels, which correlated positively with improvements in endurance and aerobic capacity. These findings demonstrate the existence of anti-inflammatory \"exercise factors\" that are transferrable, benefit the brain, and are present in humans engaging in exercise.

neuroscience↗

bioRxiv2018

Immuno-proteomic interrogation of dengue infection reveals novel HLA haplotype-specific MHC-I antigens

Broadly effective vaccines against dengue virus (DENV) infection have remained elusive, despite rising infection rates in the developing world. Infection-specific peptide ligands presented on Major Histocompatibility Complexes (MHC) open new avenues for developing T-cell-based interventions. Past efforts towards mapping viral MHC epitopes were based on computational predictions that only partially reflected actual antigen presentation. To empirically identify DENV-specific MHC ligands, we developed an immuno-proteomics approach for interrogating DENV- and self-derived MHC ligands from infected B-lymphocytes. Here, we report four fundamental findings: First, over 700 infection-specific MHC-ligands reflected host cellular responses to DENV that were not apparent from the proteome. Second, we report 121 viral MHC-I ligands (108 novel) which clustered into discrete hotspots across the DENV polyprotein, some of which spanned DENV polyprotein components, described here as MHC ligands for the first time. Third, we found DENV ligands which were distinctly presented by MHC alleles previously associated with either high or low anti-DENV response. Fourth, we demonstrate that while our in vitro assay only overlapped with a small fraction of previously described DENV T-cell epitopes, several novel MHC ligands identified here were recognized by T-cells from DENV-infected patients despite having low binding affinities. Together, these discoveries suggest that virus and host-derived MHC ligands have under-exploited potential for describing the cell biology of DENV infection, and as candidates for designing effective DENV vaccines.

immunology↗

bioRxiv2018

Measuring proteomes with long strings: A new, unconstrained paradigm in mass spectrum interpretation

Thousands of protein post-translational modifications (PTMs) dynamically impact nearly all cellular functions. Mass spectrometry is well suited to PTM identification, but proteome-scale analyses are biased towards PTMs with existing enrichment methods. To measure the full landscape of PTM regulation, software must overcome two fundamental challenges: intractably large search spaces and difficulty distinguishing correct from incorrect identifications. Here, we describe TagGraph, software that overcomes both challenges with a string-based search method orders of magnitude faster than current approaches, and probabilistic validation model optimized for PTM assignments. When applied to a human proteome map, TagGraph tripled confident identifications while revealing thousands of modification types on nearly one million sites spanning the proteome. We expand known sites by orders of magnitude for highly abundant yet understudied PTMs such as proline hydroxylation, and derive tissue-specific insight into these PTMs roles. TagGraph expands our ability to survey the full landscape of PTM function and regulation.

bioinformatics↗